From: Lukas Krickl <lukas@krickl.dev>
Date: Tue, 3 Mar 2026 11:46:20 +0000 (+0100)
Subject: map: WIP camera viewport rendering
X-Git-Url: https://git.krickl.dev/?a=commitdiff_plain;h=1eae3cf812eccfe5c9ad3924579013584db16ecd;p=lrts%2F.git

map: WIP camera viewport rendering
---

diff --git a/src/r_assets.c b/src/r_assets.c
index b68499e..05588a2 100644
--- a/src/r_assets.c
+++ b/src/r_assets.c
@@ -53,6 +53,12 @@ void r_draw_solid_isometric_tile(i32 x, i32 y, r_color color) {
 	r_color final_color;
 	struct u_vec2 t = u_tile_to_screen(x, y);
 	t = u_screen_to_camera(&t_main_camera, t);
+	
+	/* do not draw if tile is not visible at all */
+	if (!t_camera_is_visible_world(&t_main_camera, t.x, t.y)
+			&& !t_camera_is_visible_world(&t_main_camera, t.x + R_TILE_W, t.y + R_TILE_H)) {
+		return;
+	}
 
 	/* converted origin point in isometric space */
 	
diff --git a/src/t_camera.c b/src/t_camera.c
index bb60a64..896dd79 100644
--- a/src/t_camera.c
+++ b/src/t_camera.c
@@ -1,4 +1,5 @@
 #include "t_camera.h"
+#include "u_math.h"
 
 struct t_camera t_main_camera;
 
@@ -13,12 +14,21 @@ struct t_camera t_camera_init(i32 viewport_x, i32 viewport_y) {
 }
 
 void t_camera_scroll(struct t_camera *c, i32 by_x, i32 by_y) {
+	/* TODO: calculate min/max viewport based on map in a better way */
 	c->x += by_x;
 	c->y += by_y;
+}
+
+lrts_bool t_camera_is_visible_screen(struct t_camera *c, i32 x, i32 y) {
+	return u_point_in_rect(x, y, c->x, c->y, c->x + c->viewport_x, c->y + c->viewport_y);
+}
 
-	/* TODO: calculate max viewport based on map */
-	U_CLAMP(c->x, -4096, 4096);
-	U_CLAMP(c->y, -4096, 4096);
+lrts_bool t_camera_is_visible_world(struct t_camera *c, i32 x, i32 y) {
+	struct u_vec2 t;
+	t.x = c->x;
+	t.y = c->y;
+	
+	return u_point_in_rect(x, y, t.x, t.y, t.x + c->viewport_x, t.y + c->viewport_y);
 }
 
 
diff --git a/src/t_camera.h b/src/t_camera.h
index 347d349..3a9d57c 100644
--- a/src/t_camera.h
+++ b/src/t_camera.h
@@ -20,4 +20,10 @@ void t_camera_scroll(struct t_camera *c, i32 by_x, i32 by_y);
 /* adjusts a screen coodrinate by the camera offset */
 struct u_vec2 u_screen_to_camera(struct t_camera *c, struct u_vec2 v);
 
+/* tests if a point is visible in screen sapce */
+lrts_bool t_camera_is_visible_screen(struct t_camera *c, i32 x, i32 y);
+
+/* tests if a point is visible in world space */
+lrts_bool t_camera_is_visible_world(struct t_camera *c, i32 x, i32 y);
+
 #endif
diff --git a/src/t_map.c b/src/t_map.c
index 4f3995c..55608a1 100644
--- a/src/t_map.c
+++ b/src/t_map.c
@@ -26,19 +26,12 @@ void t_map_draw(struct t_map *m) {
 	struct u_vec2 start;
 	struct u_vec2 end;
 	
-	/* estimate the viewport based on the orthogonal map 
-	 * This is not perfect, but it is good enough to avoid drawing a
-	 * full size map.
-	 */
-	start.x = t_main_camera.x / R_TILE_W;
-	start.y = t_main_camera.y / R_TILE_H;
-
-	end.x = ((t_main_camera.x + t_main_camera.viewport_x) / R_TILE_W) * 2;
-	end.y = ((t_main_camera.y + t_main_camera.viewport_y) / R_TILE_H) * 2;
-
 	start.x = 0;
 	start.y = 0;
 
+	end.x = t_map.width;
+	end.y = t_map.height;
+
 	for (i = start.x; i < end.x; i++) {
 		for (j = start.y; j < end.y; j++) {
 			r_draw_tile(&m->tiles[j * m->width + i], i, j);
diff --git a/src/u_math.c b/src/u_math.c
index 52908e5..e4c40a6 100644
--- a/src/u_math.c
+++ b/src/u_math.c
@@ -19,6 +19,15 @@ struct u_vec2 u_tile_to_screen(i32 x, i32 y) {
 	return r;
 }
 
+struct u_vec2 u_point_to_screen(i32 x, i32 y) {
+	struct u_vec2 r;
+
+	r.x = (x) + (y);
+	r.y = (y) - (x);
+
+	return r;
+}
+
 lrts_bool u_point_in_rect(i32 x, i32 y, i32 rx, i32 ry, i32 rw, i32 rh) {
 	return x >= rx && x <= rx + rw
 			&& y >= ry && y <= ry + rh;
diff --git a/src/u_math.h b/src/u_math.h
index c299f55..af63f6c 100644
--- a/src/u_math.h
+++ b/src/u_math.h
@@ -50,6 +50,9 @@ struct u_vec2 u_vec2_mul(i32 n, struct u_vec2 v);
  */
 struct u_vec2 u_tile_to_screen(i32 x, i32 y);
 
+/* convers a point to screen space */
+struct u_vec2 u_point_to_screen(i32 x, i32 y);
+
 /* tests if a point is contained inside a rectangle */
 lrts_bool u_point_in_rect(i32 x, i32 y, i32 rx, i32 ry, i32 rw, i32 rh);